A striking and frequent cause of premature thelarche in children: Foeniculum vulgare.

Isolated premature thelarche is a common disorder characterized by breast development, usually younger than 2 years, with no other signs of puberty. Although it is usually associated with adrenal or ovarian disorders, hypothyroidism, and use of exogenous hormones or drugs, it may also be associated with long-term use of herbal medicine. Thus, long-term use of preparations such as Foeniculum vulgare, which is used to eliminate gas and regulate intestinal function in children, may cause premature thelarche, and thus, the use of such preparations should be limited.